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Dr. P here talking to you about the motor and

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sensory portions of the facial nerve.

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I want to come back for a minute and talk to you about the

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motor facial nerve nucleus, which sits right here.

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And then we have the abducens nerve nucleus,

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which sits right under the facial colliculus bump.

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And we've already said that there's an intimate

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relationship between the two as the motor fibers,

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predominantly, are going to loop around the abducens nerve

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and then kind of come out the side,

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where they then hit the canalicular

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portion of the facial nerve.

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So now, let's look at that portion of the facial nerve.

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It's going to be higher than the cochlear nerve.

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So, you've got to go up to see it.

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And then as it comes out right here,

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we reach the labyrinthine portion of the facial nerve.

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Then it's going to make a little curve.

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Let's make that curve known as the genu,

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and you'll have a little condensation,

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the geniculate ganglion.

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Then it has a horizontal course before

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it dives vertically,

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heading towards the parotid gland and stylomastoid foramen.

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Now, when you're in the brainstem,

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you've already seen the main facial

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nerve nucleus in the pons,

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but there is also a sensory and parasympathetic

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component to the facial nerve,

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and this is known as the intermediate nerve,

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or nervus intermedius.

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So from the brain stem,

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both the motor and sensory parts,

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join together, and they traverse the posterior cranial fossa

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before entering the petrous temporal bone

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via the IAC or internal auditory meatus.

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And then, they exit the meatus,

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as we just discussed.

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So, the take-home point here is you have

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both sensory and motor components,

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although the motor component is most

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famous and dominates the two,

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the lesser component known as the nervus intermedius.

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And you've also learned that there is, right at the genu,

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a geniculate ganglion,

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which will be discussed at a later date.

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Let's move on, shall we?